SUMOylation represses SnRK1 signaling in Arabidopsis.
SUMOylation represses SnRK1 signaling in Arabidopsis.
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DOI：
10.1111/tpj.13096
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发表时间：
2016-01
期刊：
影响因子：
--
通讯作者：
Baena-González E
中科院分区：
文献类型：
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作者：
Crozet P;Margalha L;Butowt R;Fernandes N;Elias CA;Orosa B;Tomanov K;Teige M;Bachmair A;Sadanandom A;Baena-González E
SnRK1 蛋白激酶根据细胞外条件平衡细胞能量水平，因此是植物耐逆性的关键。此外，SnRK1 还参与从种子灌浆和成熟到开花和衰老的许多生长和发育过程。尽管它很重要，但人们对调节 SnRK1 活性的机制知之甚少。在这里，我们证明了 SnRK1 复合物在多个亚基上进行了 SUMO 化，并将 SIZ1 鉴定为负责这种修饰的 E3 小泛素样修饰剂 (SUMO) 连接酶。我们进一步表明，SnRK1 以 SIZ1 依赖性方式泛素化，导致其通过蛋白酶体降解。因此，siz1-2 突变体中 SnRK1 降解存在缺陷，导致 SnRK1 信号积累和过度激活。最后，SnRK1 降解严格取决于其活性，因为无活性的 SnRK1 变体异常稳定，但当表达为 SUMO 模拟物时会恢复正常降解。总而言之，我们的数据表明，活跃的 SnRK1 会触发其自身的 SUMO 化和降解，从而建立一个负反馈回路，减弱 SnRK1 信号传导并防止应激反应的过度激活。
The SnRK1 protein kinase balances cellular energy levels in accordance with extracellular conditions and is thereby key for plant stress tolerance. In addition, SnRK1 has been implicated in numerous growth and developmental processes from seed filling and maturation to flowering and senescence. Despite its importance, the mechanisms that regulate SnRK1 activity are poorly understood. Here, we demonstrate that the SnRK1 complex is SUMOylated on multiple subunits and identify SIZ1 as the E3 Small Ubiquitin-like Modifier (SUMO) ligase responsible for this modification. We further show that SnRK1 is ubiquitinated in a SIZ1-dependent manner, causing its degradation through the proteasome. In consequence, SnRK1 degradation is deficient in siz1-2 mutants, leading to its accumulation and hyperactivation of SnRK1 signaling. Finally, SnRK1 degradation is strictly dependent on its activity, as inactive SnRK1 variants are aberrantly stable but recover normal degradation when expressed as SUMO mimetics. Altogether, our data suggest that active SnRK1 triggers its own SUMOylation and degradation, establishing a negative feedback loop that attenuates SnRK1 signaling and prevents detrimental hyperactivation of stress responses.